1. Field of the Invention
This invention relates to an image pickup element and an image pickup apparatus having an image pickup element, and more specifically, to an image pickup element which converts an optically formed image into an electrical image signal, or an image pickup apparatus provided with such an image pickup element as well as an automatic focus adjusting device and capable of obtaining an electronic image signal.
2. Related Background Art
In recent years, use of various kinds of image pickup apparatus such as digital still cameras or digital video cameras (hereinafter referred to as electronic image pickup apparatus) has become wide spread, and various techniques as to such an electronic image pickup apparatus have been disclosed and used in general practice. The electronic image pickup apparatus is constructed to photoelectrically convert an optical subject image formed by a photographing optical system such as a photographing lens into an electrical signal by using an image pickup element made of a CCD (Charge Coupled Device) and record the thus-obtained electrical image signal or video signal on a predetermined recording medium or the like as image data or video data such as digital data.
For example, there is a related art electronic image pickup apparatus having an automatic focus adjusting device (AF means) which makes detection of an in-focus position relative to a desired subject image by using an image pickup element. Such AF means moves a predetermined photographing lens or the like to the detected in-focus position by using a predetermined driving mechanism or the like, thereby automatically performing a focus adjusting operation. This type of AF means has been proposed in, for example, Japanese Patent Laid-Open No. 213737/1998, and various types of AF means have been put into practice.
The electronic image pickup apparatus disclosed in Japanese Patent Laid-Open No. 213737/1998 utilizes a so-called hill-climbing type of AF means. This hill-climbing type of AF means detects the maximum value of the contrast of an optical image (subject image) transmitted through a photographing optical system such as a photographing lens and formed on the photoconductive surface of an image pickup element, thereby finding a predetermined position of the photographing lens at this time.
Another AF means for the related art electronic image pickup apparatus is a TTL phase-difference detecting type of AF means. Various proposals have been made with respect to this type of AF means in, for example, Japanese Patent Laid-Open No. 197783/1998, Japanese Patent Publication No. 49841/1982 and Japanese Patent Laid-Open No. 274562/1998.
The AF means of the electronic image pickup apparatus disclosed in Japanese Patent Laid-Open No. 197783/1998 drives a diaphragm member to perform pupil-division processing in a time-sharing manner and causes a single image pickup element to receive a light beam passing through each aperture (pupil) of the diaphragm member, thereby detecting a phase difference.
The AF means of the electronic image pickup apparatus disclosed in Japanese Patent Publication No. 49841/1982 is a so-called fly""s eye lens system. This AF means causes a pair of photoconductive elements, each made of line sensors, to receive light beams transmitted through lens arrays, computes an image deviation quantity, i.e., a phase difference, by processing signals outputted from the line sensors, and finds, on the basis of the computational result, the amount of forward movement of a focusing lens which constitutes part of a photographing lens and is responsible for focus adjustment, thereby realizing an automatic focus adjusting operation.
The AF means of the electronic image pickup apparatus disclosed in Japanese Patent Laid-Open No. 274562/1998 is a TTL phase-difference detecting type of AF means which is called a refocusing system. This AF means converges, through a condenser lens, a light beam transmitted through a photographing lens, divides the converged light beams into two light beams by a separator lens to refocus two subject images on the photoconductive surface of a photoconductive element (a photoelectric conversion element), and detects the quantity of deviation between the two images, detecting a focus position.
In addition, Japanese Patent Laid-Open No. 201683/1996 discloses an art which relates to a refocusing type TTL phase-difference detecting device having plural focus detecting areas.
In the hill-climbing type of AF means disclosed in the above-cited Japanese Patent Laid-Open No. 213737/1998 and the like, a position at which the contrast of a subject image formed on the photoconductive surface of the image pickup element reaches a maximum is detected while the photographing lens is being moved, and then the photographing lens is made to move to a predetermined position. However, this leads to the problem that, in general, a long focus detecting time is needed and an operating speed at which to execute an automatic focus adjusting operation becomes slow.
The AF means disclosed in the above-cited Japanese Patent Laid-Open No. 197783/1998 is constructed to drive the mechanical diaphragm member to perform the pupil-division processing, and needs a driving mechanism for the diaphragm member and also needs spatial room for installation of constituent members, or the like, of the driving mechanism. It can be said, therefore, that this AF means is unfavorable for the recent strong demand for a further reduction in the size of the electronic image pickup apparatus.
In addition, in the AF means disclosed in Japanese Patent Laid-Open No. 197783/1998, since the pupil-division processing is processed in a time-division manner, a time difference occurs between obtained images. This leads to the problem that the accuracy of detection of a subject which moves at a high speed is degraded to a great extent. Moreover, in the AF means disclosed in Japanese Patent Laid-Open No. 197783/1998, since a predetermined time is needed to drive the mechanical diaphragm member, there is the problem that the speed of focus detection is lowered. In addition, it is a difficult problem to precisely retain the mechanical accuracy.
According to the AF means disclosed in the above-cited Japanese Patent Publication No. 49841/1982, Japanese Patent Laid-Open No. 274562/1998 and the like, the apparatus needs to be constructed to divide a subject light beam transmitted through the photographing lens into light beams and conduct one of the light beams to a lens array, a condenser lens and the like disposed at predetermined positions. Therefore, the AF means has the problem of being subject to optical restrictions or spatial restrictions.
In the AF means disclosed in the above-cited Japanese Patent Laid-Open No. 274562/1998, since it is necessary to newly dispose the refocusing optical system, spatial restrictions become large in the interior of the electronic image pickup apparatus, resulting in the problem of hindering the reduction of the size of the electronic image pickup apparatus.
In the AF means disclosed in the above-cited Japanese Patent Laid-Open No. 201683/1996, since a refocusing optical system and an AF sensor are needed for each of the plural focus detecting areas, there is the problem of further increases in manufacturing cost and occupied space.
A first object of the present invention is to provide an image pickup element which enables focus detecting speed to be improved without the need to newly add constituent members such as focus-detecting mechanical members or optical members which constitute a focus-detecting optical system, and without the need to increase the size of an electronic image pickup apparatus to which to apply the image pickup element, whereby further reductions in cost and space as well as a highly accurate focus adjusting function can be realized.
A second object of the present invention is to provide an image pickup apparatus having a focus adjusting function which can be reduced in cost and space because there is no need to add a new mechanism nor optical system, and which has a far wider focus detecting area and an improved AF speed and, in addition, can realize an accurate focus adjusting function.
To be brief, the invention provides an image pickup apparatus which photoelectrically converts an optical image transmitted through a photographing optical system and formed on a photoconductive surface. The image pickup apparatus includes: a first microlens array, and a second microlens array each of which has a focal position in the vicinity of the photoconductive surface and is arrayed in a two-dimensional manner; a first photoconductive element group including units each formed by a single photoconductive element which is disposed in the vicinity of the focal position of the first microlens array and outputs a first video signal; and a second photoconductive element group including units each formed by a pair of photoconductive elements which are disposed in the vicinity of the focal position of the second microlens array and output a pair of second video signals.
The invention also provides an image pickup element for use in an image pickup apparatus. The image pickup element includes: a first photoconductive element group which receives a subject light image; a first small lens group which converges a subject light beam on the first photoconductive element group; a second small lens group which divides, by pupils, a light beam transmitted through a photographing lens; and a second photoconductive element group including pairs of photoconductive elements which respectively receive light beams divided by pupils of a corresponding small lens of the second small lens group, the second small lens group and the second photoconductive element group including the pairs of photoconductive elements being formed on one chip of the image pickup element.
The invention also provides an image pickup apparatus having an image pickup element which receives and photoelectrically converts a subject light beam transmitted through a photographing optical system. The image pickup apparatus includes: an image pickup area part which has, in an arrayed manner, a first photoconductive element group which receives a subject light beam transmitted through the photographing optical system and a first small lens group which converges the subject light beam on the first photoconductive element group, the image pickup area part generating an output of the first photoconductive element group for picking up an image; and a focus detecting area part including focus detecting block columns in each of which a second small lens group and a second photoconductive element group are formed in a regularly arrayed manner and which are respectively disposed in plural areas of the image pickup element, the second small lens group dividing by pupils the subject light beam transmitted through the photographing optical system, the second photoconductive element group including pairs of photoconductive elements which respectively receive light beams divided by pupils of a corresponding small lens of the second small lens group, the focus detecting area part generating outputs of the pairs of photoconductive elements of the second photoconductive element group for the purpose of detecting focus.
The invention also provides an image pickup apparatus having an image pickup element which performs photoelectric conversion of an optical image transmitted through a photographing lens and formed on a photoconductive surface. The image pickup apparatus includes: a first small lens array and a second small lens array each of which has a focal position on the photoconductive surface and is arrayed in a two-dimensional manner; a first photoconductive element group including units each formed by a single photoconductive element which is disposed in the vicinity of the focal position of the first small lens array and outputs a first video signal; a second photoconductive element group including units each formed by a pair of photoconductive elements which are disposed in the vicinity of the focal position of the second small lens array and output a pair of second video signals; and plural focus detecting block columns in each of which the second small lens array group and the second photoconductive element group are regularly arrayed.
The invention also provides an image pickup apparatus having an image pickup element which photoelectrically converts an optical image transmitted through a photographing optical system and formed on a photoconductive surface. The image pickup apparatus includes: a first microlens array and a second microlens array each of which has a focal position in the vicinity of the photoconductive surface and is arrayed in a two-dimensional manner; a first photoconductive element group including units each formed by a single photoconductive element which is disposed in the vicinity of the focal position of the first microlens array and outputs a first video signal; and a second photoconductive element group including units each formed by a pair of photoconductive elements which are disposed in the vicinity of the focal position of the second microlens array and output a pair of second video signals.
The invention also provides an image pickup apparatus having an image pickup element which photoelectrically converts an optical image transmitted through a photographing optical system and formed on a photoconductive surface. The image pickup apparatus includes: an image pickup area part which has, in an arrayed manner, a first photoconductive element group which receives a subject light beam transmitted through the photographing optical system and a first small lens group which converges the subject light beam on the first photoconductive element group, the image pickup area part generating an output of the first photoconductive element group for picking up an image; a focus detecting area part including focus detecting block columns in each of which a second small lens group and a second photoconductive element group are formed in a regularly arrayed manner and which are respectively disposed in plural areas of the image pickup element, the second small lens group dividing, by pupils the subject light beam transmitted through the photographing optical system, the second photoconductive element group including pairs of photoconductive elements which respectively receive light beams divided by pupils of a corresponding small lens of the second small lens group, the focus detecting area part generating outputs of the pairs of photoconductive elements of the second photoconductive element group for the purpose of detecting focus; and a control means which picks up an image on the basis of the output of the first photoconductive element group of the image pickup area part, and performs focus detection on the basis of the output generated by the second photoconductive elements of the plural focus detecting block columns.
These and other objects and advantages of the invention will further become apparent from the following detailed description.
According to the present invention, it is possible to provide an image pickup element which enables focus detecting speed to be improved without the need to newly add constituent members such as mechanical members or optical members and without the need to increase the size of the electronic image pickup apparatus, whereby further reductions in cost and space, as well as a highly accurate focus adjusting function, can be realized.
According to the present invention, it is also possible to provide an image pickup apparatus having a focus adjusting function which can be reduced in cost and space because there is no need to add a new mechanism nor optical system, and which has a far wider focus detecting area and an improved AF speed and, in addition, can realize an accurate focus adjusting function.